The fabrication of some semiconductors involves fabricating a plurality of different electronic components on a substrate, such as a wafer. Due to processing requirements or the use of different materials in the electronic components, the components may have to be fabricated at different times. For example, a semiconductor may require two different types of transistors wherein each type of transistor has a gate electrode consisting of different materials. The fabrication of a second gate electrode for a second transistor may adversely affect a first gate electrode, which is fabricated at an earlier time during the fabrication process. In other words, because the second gate electrode is fabricated after the first gate electrode, the fabrication of the second gate electrode may adversely affect or damage the first gate electrode.
During the fabrication of some transistors on a substrate, a first transistor gate electrode is fabricated with several different layers and materials. A second transistor gate electrode is subsequently fabricated from at least one material, such as polysilicon. A planarization material is distributed over the substrate to protect the first gate electrode during fabrication of the second gate electrode. The planarization material is etched in the location of the second gate electrode to form an opening. The material of the second gate electrode, including the polysilicon, is applied to the substrate so that it fills the opening and forms the second gate electrode.
The height of the second gate electrode may need to be adjusted. To adjust this height, an etching process is applied to the substrate. For example, a plasma etchback process may be applied to reduce or etch the second gate electrode to a predetermined height. Performing a plasma etchback on the substrate creates a defect, such as a crown defect, on the edge of the second gate electrode proximate the planarization material. The crown defect hinders the application of subsequent materials onto the surface of the second gate electrode. Present techniques to remove the crown defect damage other materials and components on the substrate. For example, chemicals applied to the substrate to remove the crown defects may damage other materials that are exposed to the chemicals. Therefore, a need exists for a semiconductor fabrication technique that does not produce crown defects.